The present invention relates, generally, to data backup systems and methods, and more particularly, to a system and method for direct storage-to-storage copying without data passing through a virtual controller.
Organizations seeking to reduce local area network (LAN) traffic and free up more processing cycles on their servers implementing extended copy methods, also referred to as serverless backup or third-party copy. Extended copy allows a network attached storage device (NAS) to be backed up to a data storage library on a storage area network (SAN) without sending the data over the LAN or through a server. By transferring some of the bandwidth and intelligence required for backup to the SAN, the LAN and its server(s) may be freed up for other, more critical transactional data.
The extended copy command further allows data to be moved between storage devices on different buses. The backup server issues the command to a data mover in the SAN, and then removes itself from the data path. In this manner, only the source, destination and SAN devices are involved. The constraints related to the memory, I/O and CPU performance of the backup server itself are eliminated as the data moves through a high-performance copy device or agent that is optimized for data movement. Thus, a backup server may be freed up for other business-critical applications, and servers may be consolidated, since a dedicated backup server is no longer needed. Additionally, backups can complete much more quickly over higher speed networks, e.g., Fibre Channel.
The backup architecture of systems employing extended copy also may provide the ability to stream the same data to several data storage libraries or other targets simultaneously, even if they are geographically separated, without the need for copying and moving the actual data storage devices, which may be an important advantage in disaster recovery plans.
Backup equipment used in SANs is typically the same as that used in conventional configurations. What is different, however, is how these devices are interfaced to their host servers and client storage systems. Since most contemporary SANs are connected together using Fibre Channel, and since many backup devices use SCSI interfaces, a bridge is often required.
Because the extended copy command involves direct storage-to-storage copy of large quantities of data, it is intended to be very fast. However, this can be problematic when the storage device to which data is being written is a virtual storage device, e.g., a virtual controller, due to the speed demands of the extended copy function. Prior to the present invention, resolution of this issue either required the controller to possess specialized hardware to manage high-speed data rates, or else the extended copy command would suffer from slow performance due to the data copying having to pass through the virtual storage appliance (virtual controller).